Production of metals and their compounds



United States Patent PRODUCTION OF METALS AND THEIR COMPOUNDS No Drawing. Application April 18, 1949 Serial No. 88,237

Claims priority, application Great Britain April 22, 1948 2 Claims. c1. 23-309 This invention relates to the production of metals from their ores and the purification of metal compounds and is concerned with the preparation of metal compounds of a relatively high degree of purity from natural source materials or from impure compounds.

An object of the invention is to provide a simple and eflicient process whereby compounds of metals may be prepared with a reduced impurity content or substantially free from impurities. i

The invention is based on the observation that inorganic compounds, especially salts. of metals, when in solution in organic solvents are retained by adsorbent materials to an extent which varies from compound to compound and separation of selected elements from others may be achieved by appropriate choice of adsorbent and organic solvent, acidity and the valency state and salt of the element- The invention consists in separating completely or largely a metal from other metals present therewith by extracting salts of the said metal and the other metals with an organic solvent in the presence of an adsorbent material, which in the presence of the said organic solvent exhibits a different retentivity for the salt of the said metal and for the salts of the other metals.

' Preferably in accordance with the invention the adsorbent material is arranged in the form of a column to which is added a mixture of the salts of the metals to be treated, all salts preferably having a common anion, and the mixture is subjected to the leaching action of an organic solvent which then passes through the column. The eluate will contain the salt of the desired metal in those cases where the adsorbent retains more strongly the salts of the impurities. In other cases where the de sired metal salt is preferentially adsorbent or retained,

- impurities will be carried off in the eluate.

desired metal salt or salts and the salts of the impurities allpassthrough the column but at difierent rates, a fraction or fractions of the eluate containing the desired metal salt or salts may be isolated and treated for recovery of g the said metal salt or salts. 1

The mixture of metal salts to be treated, preferably 1 all having a common anion, may be added to-the column as finely powdered solids, or a slurry or concentrated 'iaqueous solution. In the latter case the solution is, preferably taken up in a small amount of the adsorbent which is then added to the top of the column. Alternatively a solution of the salts in an organic solvent may be added directly to the top of the column. In all cases leaching of the added salts is carried out by pouring further organic solvent through the column. 3

As an alternative tothe use of a column of adsorbent, successive treatmentsof a solution of the metal saltsin an organic solvent with small quantities of adsorbentmay Where a "ice A adsorbent or treated solution according to the conditions of adsorption. p v I The preferred adsorbent material is cellulose, desirably paper pulp, but cotton or scoured cottonmay be used. Paper pulp may be prepared for use in the invention by pulping in water ash-free cellulose pulp, such as is used for filtering purposes, or by disintegrating in water paper of the kind used for filtering, then filtering the resulting slurry and partially drying it as in a vacuum oven. As complete drying may lead to formation of hard lumps difficult to break up, it is preferred to maintain the-cellulose pulp moist by adding thereto the organic solvent with which it is proposed to use it. Activation of the pulp by treatment with nitric acid had been found to increase the adsorptive qualities in some cases. The activation treatment may be effected by'adding to the partially-dried. cellulose pulp referred to above suflicient concentrated nitric acid to wet it and allowing it to stand for a few minutes with the nitric acid and/or boiling it with dilute nitric acid. Water is then added and the slurry is filtered and washed until the filtrate isno longer acid. The pulp may then be shaken with alcohol, again filtered and stored either moistened with alcohol or ether or other organic solvent. Activation may also be effected by treatment of the partially dried pulp with a 4 percent hypobr mite solution in place of nitric acid.

To prepare an adsorbent column for use according to the invention a tube of glass porcelain or other inert material having a stop-cock orvalve at one end is employed. For use with organic solvent immiscible with water it has been found advantageous to give the inner wall of the tube a coating of a water repellent substance preferably dichlordimethyl silane, for example by shaking a small quantity of the substance in the tube,.or otherwise coating the inner wall, removing excess and Washing with alcohol. A perforated porcelain ,plateis then placed at the bottom of the tube to support the adsorbent column. The tube is partically filled withthe desired organic solvent and the adsorbent added in small portions at a time, each portion being stirred up with the organic solvent and gently tamped down with a plunger having a flattened head slightly smaller in diameter than the inside diameter of the tube. Voids and-irregular packingthrough which channelling of the solvent'may take place are to be avoided in preparing the column. Sufiicient adsorbent is'used to form a column approxi-. mately 10 to 25 cm. deep. If the pulp is not ash-free, a preliminary leaching with the organic solvent or solvent acid mixture is desirable before adding the salts to be treated. J I t Other adsorbents which may be employed are activate alumina, calcined ball clay, alginic acid and cation ex ethylether, tetrahydropyran, acetone, methyl-n-propyl ke-' tone also methyl acetate, ethyl butyl cellosolve and ethyl alcohol. Addition of the acid corresponding to the anion be employed, the desired salt being recovered from the of the salt being treated has been found to be advantageous in some cases, amounts of from 0.5 to 12.5 percent by volume of the concentrated acid being appropriate. The concentration of acid has been found to atfectrate of passage of some saltsthrough a column ofjadsorbent.

In carrying the invention into effect, the conditionsfor separating a desired metallic element from other metallic elements may be determined by observing the effect of a chosen adsorbent substance on salts of the said element and'other elements to be removed in the presence of an organic solvent, both in the presence and absence of the acid corresponding to the anion of the salt. The conditions giving substantially dilferent retentivity for a salt of the desired element and for salts of the elements to be removed may then be used for effecting a separation. Thus employing cellulose 'pulp'as adsorbent, metal nitrates and diethyl ether containing 12.5 percent by volume of nitric acid (d.=l.42), scandium may be separated from yttrium, cerium, praseodymium neodymium, lanthanum, samarium, ytterbium, holmium and calcium, and zirconium may be separated from hafnium. Mercury may be separated from copper and cadmium as chlorides using methyl acetate as solvent and a cellulose pulp adsorbent. The presence of sodium phosphate in the absorbent will render possible separation of mercury from bismuth also in that case. With cellulose pulp zirconium may be separated from, hafnium as nitrates using ethyl butyl Cellosolve containing 20 percent nitric acid (density 1.42) as solvent. Gold may be separated from platinum, palladium and iridium as chlorides using a cellulose pulp adsorbent and ether containing 0.5 percent of dry hydrochloric acid; Also using cellulosepulp and chlorides of the metals iridium may be separated from platinum and palladium by means of acetone containing hydrochloric acid; and the same adsorbent and organic solvent medium may be used for separating rhodium from platinum, palladium and iridium as chlorides.

The following are examples of ways of carrying the invention into efiect, the cellulose referred to in each case being of the kind employed for the production of absorbent paper, preferably filter paper, or the production of nitro-cellulose; and where activated cellulose is mentioned it is intended to refer to the product produced by treatment of such cellulose with nitric acid as described above.

EXAMPLE 1 Nickel chloride may be separated from other metal chlorides by employing an adsorbent column of cellulose pulp prepared as described above' and acetone containing 1 percent by volume of concentrated hydrochloric acid. Nickel is strongly retained on the adsorbent under such conditions-while the following elements pass through the column: copper, lead, mercury, arsenic, molybdenum, gold, platinum, palladium, iron, vanadium, zinc, cobalt and magnesium. Tin, titanium,- zireonium, chromium and. manganese do not move so readily through the column and therefore require a greater volume of solvent to obtain satisfactory separation.

In proceeding according to the example a substance, for example an ore or mixture containing nickel is converted into. an aqueous, chloride solution, which is added to a column as desribed= above and the chlorides are leached with acetone containing 1 percent by volume of concentrated hydrochloric acid. When the effluent solvent shows no metal salt or a negligible amount, leachingis discontinued and the nickel salt is washed from the column with water or with alcohol containing a little hydrochloric acid. Any aluminium, lanthanum and alkaline earth metal chlorides present as impurities are adsorbed and recovered with the nickel salt.

Methyl-n-propyl ketone may be substituted for the acetone of the example to obtain similar results. If chromium or manganese are present as impurities, however, the acidcontent of the ketone is raised in this case to 10 percent by volume to facilitate the removal of such metal chlorides.

EXAMPLE 2 Separation of mercury from copper, cadmium and bismuth A sample containing mercuric chloride (0.2046 g.), bismuth carbonate (0.2 g.), cadmium chloride (0.2 g.) and copper chloride (0.2 g.) was dissolved by treatment with 5% HCl (1 ml.) followed by addition of just enough conc. HCl to complete-solution. This liquid mixture was soaked up on a Wad of activated cellulose and transferred to the top of a column of cellulose prepared in the fol- 4 lowing manner: a glass tube (25 cm. long 2 cm. diam.) was packed to a length of 10 cm. with cellulose by agitation with methyl acetate to provide a smooth and uniform packing. A wad of pulp containing 10 ml. of a saturated sodium phosphate solution is then packed in the column as a bismuth trap, followed by a portion (2.5 cm. long) of untreated pulp on top of the phosphate trap. The wad containing the sample was then added to the column. This composite column was leached with methyl acetate ml.). The eluent was then treated with H 8 in hot solution which was allowed to cool and left for some hours. The mercuric sulphide was filtered, dried and weighed (0.1746 g.). The yield of mercury was 99.9% of the quantity originally present and spectographic analysis failed to reveal any copper, cadmium or bismuth. The object of the sodium phosphate trap mentioned above was to retain bismuth which otherwise contaminated the mercury in the methyl acetate extract.

EXAMPLE 3 Vanadium in nitric acid solution may be separated from other metals present as nitrates, or in nitric acid solution, by employing as solvent diethyl ether containing about 5 percent by volume of nitric acid (1.42 S. G.) and a column of cellulose pulp activated as described above. Vanadium travels through the column at a greater rate than lead, silver, copper, cadmium, germanium, arsenic, tin, antimony, tungsten, iron, chromium, aluminium, rare earth metals, titanium, zirconium, gallium, zinc, nickel, cobalt, manganese, alkaline earth and alkali metals, and effluent solvent substantially free from such metals and containing the vanadium may be obtained.

EXAMPLE 4 A mixture of nickel, cobalt and ferric chlorides was added to a column of cellulose pulp prepared as described above and moistened with alcohol and leached with ethyl alcohol as organic solvent. Cobalt chloridewas recovered in the first portion of the efiluent. Iron and nickel travelled down the column more slowly in that order.

A similar mixture of the chlorides, applied to a column of cellulose pulp prepared as described above and moistened with ethyl alcohol containing 1 percent of hydrochloric acid by volume, was leached withsimilar acidified ethyl alcohol. Ferric chloride was present in the first portion of the diluent and cobalt and nickel chlorides were in later portions in that order and could be collected separately.

EXAMPLE 5 (a) Separation of scandium from elements of the rare earths series A sample containing Sc O (0.128 g.), Yt O (0.25 g.) and the oxides of Ce, Pr, Nd, La, Sm (0.1 g. of each) and Yb, Ho (0.01 g. of each) was dissolved in 20% v./v. HNO (7 ml.) and the eerie salt reduced by addition of H 0 (0.5 ml. 20 vol.) followed by boiling. The cold mixture was then taken up on a wad of cellulose which was transferred to the top of a tube (2 cm. diam.) containing a column of cellulose (20 cm. long), previously prepared, using ether-nitric acid (12.5% v./v. d. 1.42 HNO solvent. Ether solvent mixture (12.5% HNO 650 ml., was then passed through the absorbent column. The eluent solvent after dilution with water and distillation of solvent followed by evaporation and calcination to oxide yielded 0.115 g. of Sc O which was shown by spectrographic analysis to be free from rare earths. The yield was 89.8% of the Sc O in the original sample.

(b) Separation of scandium from calcium A mixture of scandium (0.15 g.) and calcium (0.1 g.) as nitrates was treated as shown in Example 5(a) in a cellulose column with ether nitric acid (12.5% v./v. HN0 mixture (1 1.) All except 1 mg. of scandium i. e. 99%) was recovered from the eluent. Movement of calcium was not detected.

' It has also been observed that titanium, lead, iron, cobalt, nickel and cooper areinotextracted by diethyl ether containing 12.5 percent nitric acid under the above conditions. p

EXAMPLE- 6, Separation of zirconium M m -hafnium (a) A mixture containing ZrO (0.314 g.) and HfO (0.075 g.) was dissolved in ml. of 60% nitric acid, soaked up in a wad of activated celluloseand transferred to the top of a tube packed with cellulose to a length of cm. by agitating with a solvent mixture containing ether 87.5% and. nitric acid (d. 1.42) 12.5%by volume until a smooth uniform column was obtained. Ether-nitric acid (12.5%) mixture (600 ml.) was then allowed to percolate through the absorption tube and the zirconium recovered from the emergent liquid from the bottom of the column by evaporation and calcination. Zirconia (0.1942 g., 48.7% of the total present in the wad) was recovered and spectrographic analysis showed this oxide to be free from hafnia. Analysis of the cellulose column indicated a small quantity of hafnia at the bottom and a high proportion at the top of the column.

(b) Asample of zirconia (0.13 g.) containingapproximately hafnia Was fused with potassiumhydroxide, the melt leached with water and filtered. The residue was treated with nitric acid, evaporated just short of dryness, conc. HNO (2 ml.) added, the mixture boiled and water added until complete solution was obtained. This solution was evaporated to 3 ml., taken up in a wad of prepared cellulose and transferred to the top of a column (17 cm. long) prepared from cellulose and ethyl butyl Cellosolve (ethyl butyl ether of ethylene-glycol) containing 20% v./v. HNO (d. 1.42). Extraction was then carried out with the ethyl butyl Cellosolve and nitric acid (20%) mixture until 182 ml. of eluent had been collected. Percolation of this solvent through the column was slow. The emergent solvent contained 73% of the zirconia (0.1095 g.) which now contained only traces of hafnia. Spectrographic analysis of the cellulose column indicated a high proportion of hafnia remaining in this absorbent.

A mixture containing gold (0.1262 g.), platinum (0.04 g.), palladium (0.15 g.) and iridium (0.15 .g.) in the form of soluble chlorides in 5 N hydrochloric acid solu-- tion (0.5 ml.) was soaked up in a wad of activated cellulose and transferred to an adsorption tube containing a column (15 cm. long) of activated cellulose pulp. This column was prepared by agitating the cellulose with ether containing 0.5% dry HCl to obtain a smooth and uniform column. This solvent mixture (250 ml.), prepared by passing hydrogen chloride gas into ether until the required concentration was obtained, was allowed to percolate through the cellulose column. Gold (0.1270 g.) 100.6% was recovered from the eluent. Platinum, palladium and iridium were not detected in this recovered gold by chemical test.

EXAMPLE 8 Separation of iridium from platinum and palladium (a) A mixture containing platinum (0.1 g.), palladium (0.1 g.) and iridium (0.1 g.) as chlorides in 2 N-HCl (2 ml.) was reduced with S0 by passing the gas through the solution; iridium was thus reduced to the tervalent condition. The liquid was then soaked up in a wad of cellulose and transferred to the top of a column of cellulose (15 cm. long) prepared in the presence of dry acetone (obtained by boiling acetone with solid potash and potassium permanganate, followed by distillation) containing 2% conc. HCl, the acid being added shortly before use. Acetone-2% HCl mixture (200 ml.) was then passed through the column; practically the Whole of the and palladium was extractedand recovered.

from the eluent, whereas iridium remained'in the cellulose.

column'and could be' recovered .by leaching with dilute aqueous hydrochloric acid'orashing the cellulose to yield iridium oxide substantially free ladium.

(b) A samplecontaining 0.1 g. each of Pt, Pd and Ir; as chlorides in N-HCl (4 ml.) of solution'was reduced with S0 as in Example 5(a), soaked up on a wad of cellulose and transferred to a tube packed with cellulose from platinum and pal- (20 cm. long) in the presence of dry acetone containing Separation of rhodium from platinum, palladium and iridium In this separation rhodium was held back in the column as sodium rhodichloride (Na (RhCl while platinum, palladium and iridium were extracted. I I I A mixture containing platinum (0.3844 g.o'f H PtCl palladium (0.3156 g. of PdCl iridium (0.2032 g. of IrCl and rhodium (0.2032 g. of RhCl 2H O) was fused with Na o (2.5 gms.) and the melt taken up in dil. HCl and filtered. The residue was fused with a further portion of Na O (2.5 g.) and leached again with dil.

HCl when complete solution was achieved. The bulked solutions were evaporated to 10 ml. and dry acetone (25 ml.) added, followed by paper pulp (3 g.). This material was agitated with dry acetone containing 5% conc. HCl (25 ml.) and the liquor decanted through a column of cellulose (15 cm. long) prepared in the presence of acetone-HCl (5%) solvent mixture. The sample in the cellulose wad was stirred with successive 25 ml. portions of solvent mixture which were then poured through the column, this process being continued until 275 ml. of eluent were collected. At the conclusion of this extraction process it was found that practically all the rhodium remained in the wad with only a slight contamination due to palladium. The column contained only a trace of rhodium.

The eluents from the foregoing which were collected separately in 25 ml. portions were combined together as follows: (a) 0 to 50 m1. no metals detected; (b) 50 to ml. containing the bulk of the Pt, Pd and Ir but free from Rh, (0) 100 to 275 ml. containing traces of Pt, Pd, Ir and Rh.

The fraction (c) mixed with the wad containing the rhodium was evaporated to dryness, the residue treated with dry acetone (20 ml.) and cellulose pulp. This mixture was leached with acetone containing 10% conc. HCl, the liquors being poured through a 20 cm. cellulose column prepared in the presence of acetone containing 10% conc. HCl. This process of extraction was continued with 25 ml. portions of solvent until 200 ml. eluent was obtained. The top section of the column and the wad contained nearly all the rhodium free from Pt, Pd and Ir.

EXAMPLE 10 of iridium from platinum and palladium after removal of rhodium The separation SO, gas to reduce iridium to the tervalent condition. This reduced solution was taken up on a wad of cellulose, :transferred .to the top of a column (20 cm. long) prepared as described in Example 9(b) and extracted with acetone containing 5% come. HCl (125 m1.). Under these conditions, platinum and palladium were extracted almost entirely by the first 125 ml. of solvent, whereas nearly pure iridium was contained in the final 50 ml. of solvent eluent. The cellulose column and the wad contained the bulk of the iridium free from platinum and palladium. The iridium was recovered from the solvent by distillation and from cellulose by extraction with dilute aqueous hydrochloric acid or calcination to oxide.

In all cases, the solutions of desired salts recovered according to the examples may be worked up to produce other compounds or the metals. Solvents may be recovered by distillation, and purified for further use.

We claim:

1. A method of separating zirconium nitrate from hafnium nitrate wherein the said nitrates in admixture are added to a mass of cellulose pulp, the nitrates of the metals and the cellulose pulp are eluted with diethyl ether containing 12.5 percent by volume of nitric acid of density 1.42 and the eluent is caused to pass through a column of cellulose pulp and eflluent from the column containing zirconium nitrate substantially free from hafnium is collected.

References Cited in the file of this patent UNITED STATES PATENTS 1,423,070 Bardt July 18, 1922 1,966,729 Loomis July 17, 1934 2,075,179 Cunningham Mar. 30, 1937 2,162,936 Burrell June 20, 1939 2,184,943 Pattock Dec. 26, 1939 2,227,833 Hixson et al. Jan. 7, 1941 Hixson et al. July 22, 1941 OTHER REFERENCES Williams: An Introduction to Chromatography, 1947, Chemical Publishing Co., Inc., Brooklyn, N. Y., pp. 17- 21, 57-63.

. Strain: Chromatographic Adsorption Analysis, 1945, Interscience Publishers Inc., New York, N. Y., pp. 41-5 3, 77-82, 194. 

1. A METHOD OF SEPARATING ZIRCONIUM NITRATE FROM HAFNIUM NITRATE WHEREIN THE SAID NITRATES IN ADMIXTURE ARE ADDED TO A MASS OF CELLULOSE PULP, THE NITRATES OF THE METALS AND THE CELLULOSE PULP ARE ELUTED WITH DIETHYL ETHER CONTAINING 12.5 PERCENT BY VOLUME OF NITRIC ACID OF DENSITY 1.42 AND THE ELUENT IS CAUSED TO PASS THROUGH A COLUMN OF CELLULOSE PULP AND EFFLUENT FROM THE COLUMN CONTAINING ZIRCONIUM NITRATE SUBSTANTIALLY FREE FROM HAFNIUM IS COLLECTED. 